Seals are able to locate flatfish hiding in the sand at the bottom of the sea. This is true even if the seawater is murky and visibility is low. To find out how they do it, a team of researchers from the University of Rostock did some tests on three harbor seals.

They used very small water pumps at the sea floor to simulate the current caused as water passes through a fish's gills. "Fish produce lots of water flow that remains in the water, even after the fish has gone," said Wolf Hanke.

Then they assessed the seals' ability to locate the pumps in varying conditions: with their eyes, whiskers or faces covered or uncovered, and in clear or turbid waters.

The results showed that if there were no restrictions or hindrances, the seals located the pumps about 90 percent of the time. If they were blindfolded, the results dropped to about 75 percent of the time.

However, if the seals' whiskers were covered, the seals did not locate the pump at all—and did not even try to do so.

With this conclusion, Hanke speculates that the flatfish may pause in their breathing when there are seals swimming past, saying, "It seems conceivable that the detection of breathing currents by predators is one of the evolutionary drivers for this respiratory suppression in fish."

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